Human Reproduction vol.6 no.7 pp.953-958, 1991
The ESHRE multicentre trial on the treatment of unexplained infertility: a preliminary report*
P.G.Crosignani, D.E.WaltersM and A.Soliani II Department of Obstetrics and Gynaecology, University of Milan, Milan, Italy and 2Cambridge Research Station, Babraham Hall, Cambridge CB2 4AT, UK
Key words: randomized trials/multicentre/assisted procreation/ pregnancy rates
'To whom correspondence should be addressed
Introduction
Nineteen** European fertility centres participated in a controlled randomized trial aimed at comparing the effectiveness of five methods for the treatment of unexplained infertility. Each centre was invited to employ two of the five treatments being investigated, and the treatment allocated to individual patients was then decided by randomization. The treatments were superovulation alone, and superovulation together with one of the following procedures: intra-uterine insemination (IUI), intra-peritoneal insemination (1PT), gamete intra-Fallopian transfer (GIFT), in-vitro fertilization (TVF). All the patients admitted to the study had experienced > 36 months infertility prior to the start of the trial, and only patients < 38 years of age were included in the investigation. Further, the study was confined to patients with normal Fallopian tubes, and where there was evidence of spontaneous ovulation. Yet another prerequisite for inclusion in the study was that the male partner was 'normal' as regards fertility. Due to unavoidable practical difficulties, the experimental design eventually obtained was severely unbalanced. Nevertheless, objective statistical comparisons were possible among the Five treatments, using non-orthogonal analyses of variance. By the completion of the trial 444 patients had been treated in a total of 649 cycles. There was some statistical evidence that the pregnancy rate obtained from superovulation alone was inferior to that obtained by using superovulation together with one of the methods of assisted conception. The pregnancy rate from each method of assisted procreation was found to be vastly better than various estimates of the spontaneous pregnancy rates cited in the literature, and also of the upper limit of the pregnancy rate implied by the pre-treatment period of infertility.
Fertility clinics find that idiopathic (unexplained) infertility is still a frequent diagnosis, and of an estimated 16% of couples who are classed as infertile there appears to be no obvious cause in 10-20% of those cases. Methods of assisted procreation such as superovulation alone and superovulation allied with one of several invasive techniques, have been widely used to treat idiopathic infertility and so improve the patients' chances of becoming parents. The motivation and reasoning behind the ESHRE multicentre trial stemmed from a desire to derive an objective assessment of the effectiveness of some of the more popular methods of assisted procreation currently being practised in Europe and elsewhere. The methods to be investigated were superovulation alone, and superovulation together with one of the following procedures: intra-uterine insemination (IUI), intra-peritoneal insemination (IPI), gamete intra-Fallopian transfer (GIFT), in-vitro fertilization (TVF). A bewildering quantity of information is now continually being published relating to the effectiveness, or otherwise, of the various methods of assisted procreation in current use. However, this information is almost always derived from retrospective studies, where some subjective judgements by the clinicians and scientists would often detract from the integrity and impartiality of the resulting statistics. After some deliberation, it was decided to conduct a randomized trial with the five experimental treatments listed above, and as many as possible of the European Fertility Centres willing to participate in the venture. An obvious design for an investigation of this sort would have been a randomized complete block arrangement, whereby every centre would employ each of the five treatments in a random fashion for the patients. After some inquiries, however, it soon became apparent that, due to the highly innovative nature of some of these techniques of assisted procreation, it was quite unrealistic to expect a fertility centre to offer all five of the methods. A somewhat less regular, comprehensive, design was therefore unavoidable. Another design consideration that may be thought important in fertility studies, where there could be a strong psychological element involved, was whether to employ a placebo as a sixth (in this case) treatment. This was rejected for two reasons. It seemed quite improper to ask fertility centres to apply a 'no
•European Society of Human Reproduction and Embryology. This trial received financial support from ARES-SERONO (Geneva) **The scientists and centres who participated in the investigation were: P.Barri (Barcelona), A.Cognat (Lyon), J.Cohen (Paris), A.C.Comninos (Athens), P.G.Crosignani (Milan), K.Diedrich (Bonn), R.Frydman (Clamart), Garcea (Rome), J.Gerris (Edegem), L.Hamberger (Goteborg), Kahn (Trondheim), A.Koskimies (Helsinki), L.Mettler (Kiel), E.Muller-Ty] (Vienna), A.Pellicer (Valenicia), A.C.Van Steirteghem (Brussels), N.Willemsen (Nijmegen), P.Martinez (Amsterdam) and B.Hedon (Montpellier).
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P.G.Crosagnan], D.E.Walters and A.Soliani
treatment' option for infertile patients. Furthermore, a genuine placebo treatment would in fact be rather difficult to conceive for the invasive methods of assisted procreation. One further problem in the planning of this exercise was that different centres would inevitably display some variations in the way they applied a particular technique. Again, it seemed unreasonable to request or expect absolute experimental uniformity from the fertility centres who had so kindly volunteered to participate in the study. It was therefore conceded that the trial would in fact be testing the various treatments as customarily applied at the fertility centres. If, subsequently, it was found statistically possible to adjust for some experimental feature, perhaps by analysis of covariance, then that adjustment would certainly be made. Despite what might appear to be severe practical restrictions imposed on this investigation, it was nevertheless decided that, in view of the paucity of truly objective assessments of the efficacy of these five treatment methods, the conduct of the multicentre trial was a worthwhile, indeed a valuable, exercise. The centres who participated in the trial are to be complimented most warmly for their willing cooperation in a venture where complete scientific objectivity would not necessarily coincide with the best interests of the patients. Materials and methods Patients Patients with unexplained infertility were admitted to this study only if they satisfied certain inclusion criteria. These may be summarized as follows: (a)
The women were to be < 38 years of age and must have experienced >36 months infertility, prior to entry. (b) Only women with at least one macroscopically normal tuboovarian unit, as identified by a recent diagnostic laparoscopy, were included. (c) There must have been evidence of the occurrence of spontaneous ovulation in two recent cycles, as judged by plasma progesterone levels in the luteal phase. (d) It was necessary for the semen to be classed as 'normal' by the WHO criteria. (e) It was mandatory for patients to refrain from sexual activity for 6 days before and 3 days after the treatments. (f) There must have been a period of at least 2 months without treatment for infertility, prior to entry. Cervical and immunological infertility are still rather poorly defined at present and the interpretation of the associated tests are of dubious value. Consequently, these factors did not influence the admission of couples into the study. Experimental design In view of the practical difficulties which precluded the use of a design where all five treatments were tested at each of the centres, it was decided to invite the centres to employ only two nominated treatments, the allocation of the treatments to the individual patients then being decided by a random process. The design was therefore conceived as a 'balanced incomplete block' arrangement, with each possible pairing of treatments being tested 954 Downloaded from https://academic.oup.com/humrep/article-abstract/6/7/953/584149 by Library user on 29 April 2018
at an equal number of centres. However, as a result of the unpopularity of some of the treatments and the withdrawal of some centres from the investigation, this was again found to be impractical. The compromise design eventually obtained is displayed in Table I. Although the element of 'balance' has been lost, this design does permit an objective assessment of the effectiveness of the treatments, by making adjustments for the 'centre effect' in the statistical analysis. It will be observed that very few centres were able to accommodate the treatment method intraperitoneal insemination (IPI) and that of the total of ten possible pairings among five treatments, the following pairings were not represented in the design: IPI and GIFT, IPI and IVF, IPI and superovulation. When a patient with 'unexplained infertility' was admitted to the study, the allocation of one, or other, of the treatments for that centre was decided by a random process. If the patient did not become pregnant at the first attempt, she was encouraged to return for a second attempt, when the other treatment was then applied. The importance of this randomized trial stems directly from the conflict that inevitably exists between scientific objectivity, as represented by a designed experiment and the attainment of pregnancy, which is the dominant driving force at all fertility centres. A comparison of treatment methods where there has been a subjective judgement in the selection of the method, cannot be regarded as reliable. This trial therefore represents a rather rare event; a large scale randomized experiment where an impartial assessment of five of the methods of treating unexplained infertility is possible. A pro-forma was completed for each patient/cycle and sent to Milan, where all the available data were then entered onto a computer. The pregnancy or otherwise of the patients, which is our sole concern in this paper, was coded as follows: (1) not pregnant, (2) biochemical pregnancy, (3) aborted and (4) pregnant. For the purposes of analysis it was decided to include, initially, all clinical pregnancies, i.e. all patients with codings 3 and 4. Statistical analysis No doubt the most important variable observed in this study was the proportion of patients who became pregnant as a result of the treatment and this variable does in fact pose certain analytical difficulties. Firstly, the proportions were often found to be based on small frequencies so that the customary asymptotic statistical methods could not be regarded as reliable. The design eventually obtained was severely unbalanced on the two factors of 'centre' and 'treatment' (see above). To overcome the first difficulty, the proportions were transformed onto the logistic scale, as recommended for example by Cox (1970) and by Plackett (1983). This transformed variable was then subjected to a non-orthogonal analysis of variance, by which it was possible to adjust the pregnancy rates for the effect of 'centre' and so permit an objective study of the treatment effects. Confidence limits for individual pregnancy rates (proportions) were calculated using the method described by Walters (1985). Comparison of the pregnancy rates for the different treatments within a centre were studied by constructing 95% confidence limits on the corresponding differences, using the method
ESHRE trial for treatment of unexplained infertility
developed by Walters (1986). Similarly 95% confidence limits were calculated for the overall pregnancy rates obtained for the centres; that is after the application of one or other of the relevant treatments. These confidence limits enabled inferences to be made regarding the superiority or otherwise of these treatments when compared with other published figures. For other, more well-behaved continuous variables, the familiar classical procedures such as analyses of variance and Student's Mest were used directly, to investigate treatment effects. Results When the ESHRE multicentre trial was terminated, 444 patients had been treated in a total of 649 treatment cycles. This report was confined to the incidence of clinical pregnancies obtained, which information was complete; further results, such as numbers of babies born, or the abortion rate, will obviously need to await the final collation of the data. Pregnancy rates The pregnancy rates obtained at the first attempt, the second attempt, and from the combined data are presented in Tables II, III and IV respectively. It will be noted that a further imbalance has now appeared, due to the grossly variable numbers of patients in the sub-classes. Analyses of variance were carried out on the logistic transform of these proportions for the first attempt, the second attempt, and the combined data. In order to simplify the presentation, however, the summary statistics have been back transformed onto the original scale of proportions. For the combined data, based on 649 treatment cycles, there was evidence of a 'centre' effect and some evidence of a treatment effect. The comparison of superovulation alone, versus the remainder, was on the border-line of statistical significance at the 5% level and it would appear therefore that the application
Table I. Pairs of treatments employed by each of the 19 scientists (centres) participating in the ESHRE multi centre trial
of one of the methods of treatment had increased the chances of pregnancy beyond that obtained by superovulation alone. Table V displays the estimated mean pregnancy rates and it will be noted that for the combined data, the figures for the four invasive methods are very consistent. Indeed, the patterns are altogether very similar for all three analyses but the statistical evidence of treatment differences was only present for the combined data. It may be appropriate at this point to note a few properties of the non-orthogonal analysis of variance which it was necessary to use to investigate these data. This technique effectively estimated what the treatment mean values would have been, had all the treatments been used at each of the centres. In this way
Table 11. 'First attempt' pregnancy rates obtained f rom 444 patients, at 119 fertility• centres Centre Treatment method [UI IPl 1 2 3
0 238(5/21) 0.333 (1/3) 0.0
4
5 6 7 8 9 10 11 12 13 14
15 16 17 18 19
IVF
0.222(4/18) 0.000 (0/8) 0.000 (0/3)
0.091
(1/11)
0.262 (11/42) 0.571 (4/7)
0.000 (0/12) 0.154 (2/13) 0400 (2/5)
0 250(3/12) 0.000 (0/2)
1.000 (1/1)
0 500 (9/18)
0 333 (2/6) 0.360 (9/25)
0 000 (0/7) 0.250(1/4) 0.500 (1/2) 0 000(0/10) 0.500 (4/8) 0 278 (5/18)
Superovulation
0.000 (0/9) 0 333 (3/9)
(0/3)
0 229 (11/48) 0 267(4/15)
GIFT
0.091 (1/H)
O.OOO
(0/5)
1.000 (1/1) 0.000 (0/5)
0.000(0/2)
0 118 (2/17) 0.636 (7/11) 0.400 (2/5)
0 429 (3/7) 0 067 (1/15)
0.400 (4/10) 0.133 (2/15)
The data are of proportions which are followed, in brackets, by the frequencies involved. These are the results at the completion of the ESHRE multicentre trial
Treatment Centre no.
Name of scientist
IUI
( 1) ( 2) ( 3) ( 4) ( 5) ( 6) ( 7) ( 8) ( 9) (10)
Barn Cognat Comninos Crosignani Diedrich Frydman Garcea Gerris Hamberger Hedon Koskimies Mettler Willemsen Cohen Kahn Pellicer Van Steirteghem Muller-Tyl Martinez
X
(11)
(12) (13)
(14) (15) (16) (17) (18) (19)
IPI
GIFT
IVF
Superovulation
Centre Treatment method IPI IUI
X
1
X X
X
X X
X X
X X
X X
X X X X
X X X
0.538 (7/13) 0.000 (0/1)
4
12 13 14
15 16 18 19
GIFT 0.200 (3/15) 0.333 (2/6)
2 6 7 g 10
X
X X
Table III. Second attempt' pregnancy rates obtained from 205 patients, at 14 fertility clinics Superovulation
0.000 (0/2) 0.333(1/3)
0.000(0/7)
0.189 (7/37) 0.000 (0/2)
0 161 (5/31) 0.200 (2/10) 0000 (0/1)
IVF
0.000 (0/4)
0.091 (1/11) 0.000 (0/3)
0000 (0/5) 0.000 (0/2) 0.000 (0/1) 0.250 (1/4) 0.667 (2/3) 0.154 (2/13)
0.000 (0/1) 0.333 (2/6) 0.750 (3/4) 0.000 (0/2) 1.000 (4/4) 0.000 (0/14)
X
The data are of proportions which are followed, in brackets, by the frequencies involved. These figures comprise the complete data of 'second attempts', at the end of the multicentre trial.
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P.G.Crosigiiani, D.E.Wahers and A.Solianl
Table IV. Combined 'per cycle' pregnancy rates obtained from 649 treatment cycles, distributed over 444 patients and 19 fertility clinics Centre Treatment method IUI IPI 1
2 3
0 333 (1/3)
GIFT
IVF
0.212 (7/33) 0.143 (2/14) 0000 (0/3)
0.077 (1/13)
0.0 (0/4) 0.203 (16/79)
8
0.240 (6/25)
9 10 11 12 13 14 15 16 17 18 19
0.228 (18/79) 0.444 (4/9)
(1/7) (0/12) (4/9) (6/22)
u 6 8.4
I 3 -
0.222 (2/9)
0000 (0/2)
1.000 (1/1)
0.429 (9/21)
0.333 (2/6) 0 360 (9/25)
£
8.1 -
0.000 (0/6) 0.250 (2/8)
Estlmoted Spontaneous Pregnancy Rote
1.000 (1/1) 0.333 (3/9) 0.105 (2/19) 0.636 (7/11) 0 667 (6/9)
0.400 (4/10)
' ' '^ 1 1
' ' I ' 2 Treatment
0.O69 (2/29)
The data arc of proportions which are followed, in brackets, by the frequencies involved. These are the complete data at the conclusion of the ESHRE multicentre trial
Table V. Estimated mean pregnancy rates for the five experimental treatments, derived from the statistical analysis
IUI IPI GIFT IVF Superovulation
C C71 01
0.091 (1/11)
0.500 (5/10) 0.107 (3/28)
Method
IVF Super
0.174(4/23)
0.000 (0/8) 0 250 (1/4) 0.143 0.000 0.444 0.273
GIFT
Superovulation
0.083 (1/12) 0.000 (0/19) 0.333 (3/9) 0.154 (2/13)
5 6 7
IPI
8.5 -
0.353 (12/34)
4
IUI
Pregnancy rate/cycle First Second
Combined
0.271 0.299 0.284 0 237 0.174
0.274 0.270 0.280 0.257 0.152
0.283 0.257 0.257 0.380 0.116
'Significance probability for the comparison superovulation versus the remainder was 0.058.
Estlmoted Spontaneous Pregnancy Rote
Centre
Fig. 1. First attempt pregnancy rates and 95% confidence limits at selected centres (ESHRE multicentre trial).
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Fig. 2. Mean (per cycle) pregnancy rates and 95% confidence limits for the five treatments (ESHRE multicentre trial).
the treatment means were adjusted for any inter-centre differences that were present. The need for this rather complex computational device was due to the severe imbalance of the design eventually obtained and to the unequal numbers in the sub-classes. Because of non-orthogonality, it is sometimes difficult to reconcile treatment mean values with the original data, as indeed was the case here. Further details of the pregnancy rates obtained in this study are presented in Figures 1 and 2. Figure 1 is a plot of the first attempt pregnancy rate at selected centres. This plot was confined to those centres for which there were a reasonable number of patients and excluded the centres using superovulation which returned a lower pregnancy rate. The pregnancy rates plotted were therefore pooled figures for two of the invasive techniques. Figure 2 is a plot of the estimated mean pregnancy rates for the four treatments. The 95% confidence limits on the estimated pregnancy rates were plotted on both of the diagrams and a horizontal line drawn to provide some indication of the expected spontaneous pregnancy rate (see below). Spontaneous pregnancy rates The pregnancy rates obtained in this trial were compared with various estimates of the spontaneous pregnancy rates that have been cited in the literature, namely those associated with the same period of infertility (>36 months). Collins et al. (1984) cited some cumulative pregnancy rates after 12 and 36 months, of 89 patients who had previously experienced a period of unexplained infertility of >36 months. Using the simplest binomial model, that the monthly probability of becoming pregnant was '/?', independently for each month, then the probability of pregnancy after 'k' months was given by: Probability = 1 - (1 - p)k For a cumulative pregnancy rate, this formula was used to estimate ' p \ the monthly probability of pregnancy. Using the
ESHRE trial for treatment of unexplained infertility
figures of 13.5% and 40.5% respectively (Collins et al., 1984) as the cumulative pregnancy rates after 12 and 36 months, we obtained estimates of 0.012 and 0.014 as the 'per month' probability. It was very encouraging indeed, and perhaps added credibility to the model, that these two estimates were so close. Collins et al. (1984) also quoted 95% confidence limits on the cumulative rates and applying the above formula to the upper limits gave 0.019 and 0.024 as the upper limit for 'p'. Based on these figures applied to the simple model, therefore, we were 95% confident that the true value of '/?' was lower than those upper limits quoted. J.A.Collins (personal communication) also supplied spontaneous pregnancy rates for a further group of 73 patients who had been infertile for >36 months. The subsequent pregnancy rate in the first month was found to be 0.027, with rather broad 95% confidence limits of 0.008 and 0.094. The values of Lp' derived from later cumulative results from the same data set, however, suggested a rather lower figure. In this context, it would seem quite reasonable after such a long period of infertility to regard pregnancy as having a very small, constant probability, rather than a decreasing value. It must be acknowledged, nevertheless, that estimating the 'per month' pregnancy rates in this way made some severe assumptions about the patient's sexual activity during the study period. Bringing together the various pieces of information presented above, it would seem that the monthly, spontaneous pregnancy rate for patients with > 36 months infertility may be around 2 %, and could indeed be a good deal lower. Thus it is a figure of this magnitude that we need to compare with the 'assisted procreation' figures quoted earlier. Another way of quantifying the 'no treatment' probability of pregnancy was to use the fact that patients admitted to this study had been infertile for 36 months. An upper 95% point for zero response in 36 attempts was 0.078. We concluded therefore, for the 'infertile' period, that we were 95% confident that the unknown 'spontaneous' pregnancy rate for the study group of patients was
The ESHRE multicentre trial on the treatment of unexplained infertility: a preliminary report*
P.G.Crosignani, D.E.WaltersM and A.Soliani II Department of Obstetrics and Gynaecology, University of Milan, Milan, Italy and 2Cambridge Research Station, Babraham Hall, Cambridge CB2 4AT, UK
Key words: randomized trials/multicentre/assisted procreation/ pregnancy rates
'To whom correspondence should be addressed
Introduction
Nineteen** European fertility centres participated in a controlled randomized trial aimed at comparing the effectiveness of five methods for the treatment of unexplained infertility. Each centre was invited to employ two of the five treatments being investigated, and the treatment allocated to individual patients was then decided by randomization. The treatments were superovulation alone, and superovulation together with one of the following procedures: intra-uterine insemination (IUI), intra-peritoneal insemination (1PT), gamete intra-Fallopian transfer (GIFT), in-vitro fertilization (TVF). All the patients admitted to the study had experienced > 36 months infertility prior to the start of the trial, and only patients < 38 years of age were included in the investigation. Further, the study was confined to patients with normal Fallopian tubes, and where there was evidence of spontaneous ovulation. Yet another prerequisite for inclusion in the study was that the male partner was 'normal' as regards fertility. Due to unavoidable practical difficulties, the experimental design eventually obtained was severely unbalanced. Nevertheless, objective statistical comparisons were possible among the Five treatments, using non-orthogonal analyses of variance. By the completion of the trial 444 patients had been treated in a total of 649 cycles. There was some statistical evidence that the pregnancy rate obtained from superovulation alone was inferior to that obtained by using superovulation together with one of the methods of assisted conception. The pregnancy rate from each method of assisted procreation was found to be vastly better than various estimates of the spontaneous pregnancy rates cited in the literature, and also of the upper limit of the pregnancy rate implied by the pre-treatment period of infertility.
Fertility clinics find that idiopathic (unexplained) infertility is still a frequent diagnosis, and of an estimated 16% of couples who are classed as infertile there appears to be no obvious cause in 10-20% of those cases. Methods of assisted procreation such as superovulation alone and superovulation allied with one of several invasive techniques, have been widely used to treat idiopathic infertility and so improve the patients' chances of becoming parents. The motivation and reasoning behind the ESHRE multicentre trial stemmed from a desire to derive an objective assessment of the effectiveness of some of the more popular methods of assisted procreation currently being practised in Europe and elsewhere. The methods to be investigated were superovulation alone, and superovulation together with one of the following procedures: intra-uterine insemination (IUI), intra-peritoneal insemination (IPI), gamete intra-Fallopian transfer (GIFT), in-vitro fertilization (TVF). A bewildering quantity of information is now continually being published relating to the effectiveness, or otherwise, of the various methods of assisted procreation in current use. However, this information is almost always derived from retrospective studies, where some subjective judgements by the clinicians and scientists would often detract from the integrity and impartiality of the resulting statistics. After some deliberation, it was decided to conduct a randomized trial with the five experimental treatments listed above, and as many as possible of the European Fertility Centres willing to participate in the venture. An obvious design for an investigation of this sort would have been a randomized complete block arrangement, whereby every centre would employ each of the five treatments in a random fashion for the patients. After some inquiries, however, it soon became apparent that, due to the highly innovative nature of some of these techniques of assisted procreation, it was quite unrealistic to expect a fertility centre to offer all five of the methods. A somewhat less regular, comprehensive, design was therefore unavoidable. Another design consideration that may be thought important in fertility studies, where there could be a strong psychological element involved, was whether to employ a placebo as a sixth (in this case) treatment. This was rejected for two reasons. It seemed quite improper to ask fertility centres to apply a 'no
•European Society of Human Reproduction and Embryology. This trial received financial support from ARES-SERONO (Geneva) **The scientists and centres who participated in the investigation were: P.Barri (Barcelona), A.Cognat (Lyon), J.Cohen (Paris), A.C.Comninos (Athens), P.G.Crosignani (Milan), K.Diedrich (Bonn), R.Frydman (Clamart), Garcea (Rome), J.Gerris (Edegem), L.Hamberger (Goteborg), Kahn (Trondheim), A.Koskimies (Helsinki), L.Mettler (Kiel), E.Muller-Ty] (Vienna), A.Pellicer (Valenicia), A.C.Van Steirteghem (Brussels), N.Willemsen (Nijmegen), P.Martinez (Amsterdam) and B.Hedon (Montpellier).
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P.G.Crosagnan], D.E.Walters and A.Soliani
treatment' option for infertile patients. Furthermore, a genuine placebo treatment would in fact be rather difficult to conceive for the invasive methods of assisted procreation. One further problem in the planning of this exercise was that different centres would inevitably display some variations in the way they applied a particular technique. Again, it seemed unreasonable to request or expect absolute experimental uniformity from the fertility centres who had so kindly volunteered to participate in the study. It was therefore conceded that the trial would in fact be testing the various treatments as customarily applied at the fertility centres. If, subsequently, it was found statistically possible to adjust for some experimental feature, perhaps by analysis of covariance, then that adjustment would certainly be made. Despite what might appear to be severe practical restrictions imposed on this investigation, it was nevertheless decided that, in view of the paucity of truly objective assessments of the efficacy of these five treatment methods, the conduct of the multicentre trial was a worthwhile, indeed a valuable, exercise. The centres who participated in the trial are to be complimented most warmly for their willing cooperation in a venture where complete scientific objectivity would not necessarily coincide with the best interests of the patients. Materials and methods Patients Patients with unexplained infertility were admitted to this study only if they satisfied certain inclusion criteria. These may be summarized as follows: (a)
The women were to be < 38 years of age and must have experienced >36 months infertility, prior to entry. (b) Only women with at least one macroscopically normal tuboovarian unit, as identified by a recent diagnostic laparoscopy, were included. (c) There must have been evidence of the occurrence of spontaneous ovulation in two recent cycles, as judged by plasma progesterone levels in the luteal phase. (d) It was necessary for the semen to be classed as 'normal' by the WHO criteria. (e) It was mandatory for patients to refrain from sexual activity for 6 days before and 3 days after the treatments. (f) There must have been a period of at least 2 months without treatment for infertility, prior to entry. Cervical and immunological infertility are still rather poorly defined at present and the interpretation of the associated tests are of dubious value. Consequently, these factors did not influence the admission of couples into the study. Experimental design In view of the practical difficulties which precluded the use of a design where all five treatments were tested at each of the centres, it was decided to invite the centres to employ only two nominated treatments, the allocation of the treatments to the individual patients then being decided by a random process. The design was therefore conceived as a 'balanced incomplete block' arrangement, with each possible pairing of treatments being tested 954 Downloaded from https://academic.oup.com/humrep/article-abstract/6/7/953/584149 by Library user on 29 April 2018
at an equal number of centres. However, as a result of the unpopularity of some of the treatments and the withdrawal of some centres from the investigation, this was again found to be impractical. The compromise design eventually obtained is displayed in Table I. Although the element of 'balance' has been lost, this design does permit an objective assessment of the effectiveness of the treatments, by making adjustments for the 'centre effect' in the statistical analysis. It will be observed that very few centres were able to accommodate the treatment method intraperitoneal insemination (IPI) and that of the total of ten possible pairings among five treatments, the following pairings were not represented in the design: IPI and GIFT, IPI and IVF, IPI and superovulation. When a patient with 'unexplained infertility' was admitted to the study, the allocation of one, or other, of the treatments for that centre was decided by a random process. If the patient did not become pregnant at the first attempt, she was encouraged to return for a second attempt, when the other treatment was then applied. The importance of this randomized trial stems directly from the conflict that inevitably exists between scientific objectivity, as represented by a designed experiment and the attainment of pregnancy, which is the dominant driving force at all fertility centres. A comparison of treatment methods where there has been a subjective judgement in the selection of the method, cannot be regarded as reliable. This trial therefore represents a rather rare event; a large scale randomized experiment where an impartial assessment of five of the methods of treating unexplained infertility is possible. A pro-forma was completed for each patient/cycle and sent to Milan, where all the available data were then entered onto a computer. The pregnancy or otherwise of the patients, which is our sole concern in this paper, was coded as follows: (1) not pregnant, (2) biochemical pregnancy, (3) aborted and (4) pregnant. For the purposes of analysis it was decided to include, initially, all clinical pregnancies, i.e. all patients with codings 3 and 4. Statistical analysis No doubt the most important variable observed in this study was the proportion of patients who became pregnant as a result of the treatment and this variable does in fact pose certain analytical difficulties. Firstly, the proportions were often found to be based on small frequencies so that the customary asymptotic statistical methods could not be regarded as reliable. The design eventually obtained was severely unbalanced on the two factors of 'centre' and 'treatment' (see above). To overcome the first difficulty, the proportions were transformed onto the logistic scale, as recommended for example by Cox (1970) and by Plackett (1983). This transformed variable was then subjected to a non-orthogonal analysis of variance, by which it was possible to adjust the pregnancy rates for the effect of 'centre' and so permit an objective study of the treatment effects. Confidence limits for individual pregnancy rates (proportions) were calculated using the method described by Walters (1985). Comparison of the pregnancy rates for the different treatments within a centre were studied by constructing 95% confidence limits on the corresponding differences, using the method
ESHRE trial for treatment of unexplained infertility
developed by Walters (1986). Similarly 95% confidence limits were calculated for the overall pregnancy rates obtained for the centres; that is after the application of one or other of the relevant treatments. These confidence limits enabled inferences to be made regarding the superiority or otherwise of these treatments when compared with other published figures. For other, more well-behaved continuous variables, the familiar classical procedures such as analyses of variance and Student's Mest were used directly, to investigate treatment effects. Results When the ESHRE multicentre trial was terminated, 444 patients had been treated in a total of 649 treatment cycles. This report was confined to the incidence of clinical pregnancies obtained, which information was complete; further results, such as numbers of babies born, or the abortion rate, will obviously need to await the final collation of the data. Pregnancy rates The pregnancy rates obtained at the first attempt, the second attempt, and from the combined data are presented in Tables II, III and IV respectively. It will be noted that a further imbalance has now appeared, due to the grossly variable numbers of patients in the sub-classes. Analyses of variance were carried out on the logistic transform of these proportions for the first attempt, the second attempt, and the combined data. In order to simplify the presentation, however, the summary statistics have been back transformed onto the original scale of proportions. For the combined data, based on 649 treatment cycles, there was evidence of a 'centre' effect and some evidence of a treatment effect. The comparison of superovulation alone, versus the remainder, was on the border-line of statistical significance at the 5% level and it would appear therefore that the application
Table I. Pairs of treatments employed by each of the 19 scientists (centres) participating in the ESHRE multi centre trial
of one of the methods of treatment had increased the chances of pregnancy beyond that obtained by superovulation alone. Table V displays the estimated mean pregnancy rates and it will be noted that for the combined data, the figures for the four invasive methods are very consistent. Indeed, the patterns are altogether very similar for all three analyses but the statistical evidence of treatment differences was only present for the combined data. It may be appropriate at this point to note a few properties of the non-orthogonal analysis of variance which it was necessary to use to investigate these data. This technique effectively estimated what the treatment mean values would have been, had all the treatments been used at each of the centres. In this way
Table 11. 'First attempt' pregnancy rates obtained f rom 444 patients, at 119 fertility• centres Centre Treatment method [UI IPl 1 2 3
0 238(5/21) 0.333 (1/3) 0.0
4
5 6 7 8 9 10 11 12 13 14
15 16 17 18 19
IVF
0.222(4/18) 0.000 (0/8) 0.000 (0/3)
0.091
(1/11)
0.262 (11/42) 0.571 (4/7)
0.000 (0/12) 0.154 (2/13) 0400 (2/5)
0 250(3/12) 0.000 (0/2)
1.000 (1/1)
0 500 (9/18)
0 333 (2/6) 0.360 (9/25)
0 000 (0/7) 0.250(1/4) 0.500 (1/2) 0 000(0/10) 0.500 (4/8) 0 278 (5/18)
Superovulation
0.000 (0/9) 0 333 (3/9)
(0/3)
0 229 (11/48) 0 267(4/15)
GIFT
0.091 (1/H)
O.OOO
(0/5)
1.000 (1/1) 0.000 (0/5)
0.000(0/2)
0 118 (2/17) 0.636 (7/11) 0.400 (2/5)
0 429 (3/7) 0 067 (1/15)
0.400 (4/10) 0.133 (2/15)
The data are of proportions which are followed, in brackets, by the frequencies involved. These are the results at the completion of the ESHRE multicentre trial
Treatment Centre no.
Name of scientist
IUI
( 1) ( 2) ( 3) ( 4) ( 5) ( 6) ( 7) ( 8) ( 9) (10)
Barn Cognat Comninos Crosignani Diedrich Frydman Garcea Gerris Hamberger Hedon Koskimies Mettler Willemsen Cohen Kahn Pellicer Van Steirteghem Muller-Tyl Martinez
X
(11)
(12) (13)
(14) (15) (16) (17) (18) (19)
IPI
GIFT
IVF
Superovulation
Centre Treatment method IPI IUI
X
1
X X
X
X X
X X
X X
X X
X X X X
X X X
0.538 (7/13) 0.000 (0/1)
4
12 13 14
15 16 18 19
GIFT 0.200 (3/15) 0.333 (2/6)
2 6 7 g 10
X
X X
Table III. Second attempt' pregnancy rates obtained from 205 patients, at 14 fertility clinics Superovulation
0.000 (0/2) 0.333(1/3)
0.000(0/7)
0.189 (7/37) 0.000 (0/2)
0 161 (5/31) 0.200 (2/10) 0000 (0/1)
IVF
0.000 (0/4)
0.091 (1/11) 0.000 (0/3)
0000 (0/5) 0.000 (0/2) 0.000 (0/1) 0.250 (1/4) 0.667 (2/3) 0.154 (2/13)
0.000 (0/1) 0.333 (2/6) 0.750 (3/4) 0.000 (0/2) 1.000 (4/4) 0.000 (0/14)
X
The data are of proportions which are followed, in brackets, by the frequencies involved. These figures comprise the complete data of 'second attempts', at the end of the multicentre trial.
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P.G.Crosigiiani, D.E.Wahers and A.Solianl
Table IV. Combined 'per cycle' pregnancy rates obtained from 649 treatment cycles, distributed over 444 patients and 19 fertility clinics Centre Treatment method IUI IPI 1
2 3
0 333 (1/3)
GIFT
IVF
0.212 (7/33) 0.143 (2/14) 0000 (0/3)
0.077 (1/13)
0.0 (0/4) 0.203 (16/79)
8
0.240 (6/25)
9 10 11 12 13 14 15 16 17 18 19
0.228 (18/79) 0.444 (4/9)
(1/7) (0/12) (4/9) (6/22)
u 6 8.4
I 3 -
0.222 (2/9)
0000 (0/2)
1.000 (1/1)
0.429 (9/21)
0.333 (2/6) 0 360 (9/25)
£
8.1 -
0.000 (0/6) 0.250 (2/8)
Estlmoted Spontaneous Pregnancy Rote
1.000 (1/1) 0.333 (3/9) 0.105 (2/19) 0.636 (7/11) 0 667 (6/9)
0.400 (4/10)
' ' '^ 1 1
' ' I ' 2 Treatment
0.O69 (2/29)
The data arc of proportions which are followed, in brackets, by the frequencies involved. These are the complete data at the conclusion of the ESHRE multicentre trial
Table V. Estimated mean pregnancy rates for the five experimental treatments, derived from the statistical analysis
IUI IPI GIFT IVF Superovulation
C C71 01
0.091 (1/11)
0.500 (5/10) 0.107 (3/28)
Method
IVF Super
0.174(4/23)
0.000 (0/8) 0 250 (1/4) 0.143 0.000 0.444 0.273
GIFT
Superovulation
0.083 (1/12) 0.000 (0/19) 0.333 (3/9) 0.154 (2/13)
5 6 7
IPI
8.5 -
0.353 (12/34)
4
IUI
Pregnancy rate/cycle First Second
Combined
0.271 0.299 0.284 0 237 0.174
0.274 0.270 0.280 0.257 0.152
0.283 0.257 0.257 0.380 0.116
'Significance probability for the comparison superovulation versus the remainder was 0.058.
Estlmoted Spontaneous Pregnancy Rote
Centre
Fig. 1. First attempt pregnancy rates and 95% confidence limits at selected centres (ESHRE multicentre trial).
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Fig. 2. Mean (per cycle) pregnancy rates and 95% confidence limits for the five treatments (ESHRE multicentre trial).
the treatment means were adjusted for any inter-centre differences that were present. The need for this rather complex computational device was due to the severe imbalance of the design eventually obtained and to the unequal numbers in the sub-classes. Because of non-orthogonality, it is sometimes difficult to reconcile treatment mean values with the original data, as indeed was the case here. Further details of the pregnancy rates obtained in this study are presented in Figures 1 and 2. Figure 1 is a plot of the first attempt pregnancy rate at selected centres. This plot was confined to those centres for which there were a reasonable number of patients and excluded the centres using superovulation which returned a lower pregnancy rate. The pregnancy rates plotted were therefore pooled figures for two of the invasive techniques. Figure 2 is a plot of the estimated mean pregnancy rates for the four treatments. The 95% confidence limits on the estimated pregnancy rates were plotted on both of the diagrams and a horizontal line drawn to provide some indication of the expected spontaneous pregnancy rate (see below). Spontaneous pregnancy rates The pregnancy rates obtained in this trial were compared with various estimates of the spontaneous pregnancy rates that have been cited in the literature, namely those associated with the same period of infertility (>36 months). Collins et al. (1984) cited some cumulative pregnancy rates after 12 and 36 months, of 89 patients who had previously experienced a period of unexplained infertility of >36 months. Using the simplest binomial model, that the monthly probability of becoming pregnant was '/?', independently for each month, then the probability of pregnancy after 'k' months was given by: Probability = 1 - (1 - p)k For a cumulative pregnancy rate, this formula was used to estimate ' p \ the monthly probability of pregnancy. Using the
ESHRE trial for treatment of unexplained infertility
figures of 13.5% and 40.5% respectively (Collins et al., 1984) as the cumulative pregnancy rates after 12 and 36 months, we obtained estimates of 0.012 and 0.014 as the 'per month' probability. It was very encouraging indeed, and perhaps added credibility to the model, that these two estimates were so close. Collins et al. (1984) also quoted 95% confidence limits on the cumulative rates and applying the above formula to the upper limits gave 0.019 and 0.024 as the upper limit for 'p'. Based on these figures applied to the simple model, therefore, we were 95% confident that the true value of '/?' was lower than those upper limits quoted. J.A.Collins (personal communication) also supplied spontaneous pregnancy rates for a further group of 73 patients who had been infertile for >36 months. The subsequent pregnancy rate in the first month was found to be 0.027, with rather broad 95% confidence limits of 0.008 and 0.094. The values of Lp' derived from later cumulative results from the same data set, however, suggested a rather lower figure. In this context, it would seem quite reasonable after such a long period of infertility to regard pregnancy as having a very small, constant probability, rather than a decreasing value. It must be acknowledged, nevertheless, that estimating the 'per month' pregnancy rates in this way made some severe assumptions about the patient's sexual activity during the study period. Bringing together the various pieces of information presented above, it would seem that the monthly, spontaneous pregnancy rate for patients with > 36 months infertility may be around 2 %, and could indeed be a good deal lower. Thus it is a figure of this magnitude that we need to compare with the 'assisted procreation' figures quoted earlier. Another way of quantifying the 'no treatment' probability of pregnancy was to use the fact that patients admitted to this study had been infertile for 36 months. An upper 95% point for zero response in 36 attempts was 0.078. We concluded therefore, for the 'infertile' period, that we were 95% confident that the unknown 'spontaneous' pregnancy rate for the study group of patients was
